Our long-term objective is to develop new approaches for the treatment of tuberculosis (TB) by studying the host genetic factors controlling the development of effective cellular immunity against M. tuberculosis (Mtb). We have preliminary data showing that the genotype GG in the promoter region of MCP-1 is present in 50% of individuals susceptible to TB. This genotype produces this trait by a mechanism that may involve increased production of MCP-l and MCP-l inhibition of IL-12 production through the down-modulation of Osteopontin (Opn) receptor alphaVbeta33 in macrophages. In specific aim 1, we seek to confirm the association of the genotype GG with susceptibility to TB in a two-step case/control and a family study with parental samples of affected individuals and a TDT (Transmission-Disequilibrium Test). The sample for the case/control studies will comprise a large and rigorously characterized group of unrelated individuals with active TB and controls. Plasma samples from these individuals will be used to determine the levels of MCP-l, IL-12, IL-10, IFN-gamma and Opn to uncover the effect of MCP-l on the levels of these factors. With the same purpose, PBMC from a limited number (20 of each genotype) of these fully typed TB cases and controls will be stimulated in vitro with Mtb antigens and the levels of factors mentioned above measured. In specific aim 2, we will extend our preliminary studies to characterize in vitro the effect of MCP-l in alphaVbeta33 and CD44 Opn receptors, CD14 and TLR-2, and CD40 and CD154 expression and its relevance in the modulation of IL-12, MCP-l, IL-10, and Opn production in response to Mtb antigens. We also seek to determine if alphaVbeta3/CD44, CD14/TLR-2, and CD40/CD154 have additive effects in the induction of IL-12, and how they interact to modulate each other, and how MCP-l affects these pathways and these pathways interaction. In specific aim 3, we will explore in vitro how mycobacterial infection affects the production of MCP-l, IL-12, IL-10, and Opn and the expression of alphaVbeta3, CD44, CD14, TLR-2, CD40 and CD154. To achieve our goals in specific aim 1, Dr. Julio Granados, Chairman Investigator, Dept. Immunology, Mexican Institute of Nutrition, will be our consultant and collaborator. He and Dr. Moises Selman, from the Mexican Institute of Respiratory Diseases will recruit the TB cases and controls, process blood samples to isolate DNA, plasma, and PBMC. The PBMC will be stimulated in vitro in Dr. Granados' laboratory. The DNA samples will be sent to Boston where they will be typed. The plasma samples and culture supernatants will be kept frozen until we pick them up (twice a year) and bring them to Boston in vaporize-liquid nitrogen tanks for further analysis. For specific aims 2 and 3, we will use leukophoresis products from fully type- selected individuals of a panel of 200 healthy donors residents in Boston.